An age-old problem has been to increase the load-carrying capacity of a pile and to increase its resistance against pullout in sandy or other granular soil, for example. Another problem has been the temporary joining of two tubes or cylinders, as when erecting an offshore tower with telescopic leg joints underwater to be held in place until permanently joined or fixed in position. Another problem is to temporarily join two cylinders without expensive and costly prior preparation.
The disclosed invention is an improvement over my prior methods and mechanisms for connecting two telescopic tubes together underwater illustrated in my U.S. Pat. No. 3,555,831, of Jan. 19, 1971, or U.S. Pat. No. 3,834,012 of Sept. 10, 1974. Other examples of increasing pile pullout resistance as by forming corrugations or bumps are disclosed in U.S. Pat. No. 3,453,831(7-69); U.S. Pat. No. 3,375,670 (4-68); British Pat. No. 1,034,128 of 1964; and German Pat. No. 599,785 of 1934, over which the disclosed invention is a substantial improvement.